1. Epidemiology Department, High Institute of Public Health, Alexandria University, Alexandria, Egypt.
2. Department of Physiology and Biochemistry, School of Medicine, The University of Jordan, Amman, Jordan.
3. Department of Clinical pathology, National Cancer Institute, Cairo University, Cairo, Egypt.
4. Department of Physical Medicine, Rheumatology and Rehabilitation, Faculty of Medicine, Suez Canal University, Ismailia, Egypt.
5. Cairo, Egypt.
6. Department of Orthodontics, Pediatric dentistry and Preventive dentistry, Faculty of Dentistry, University of Khartoum, Khartoum, Sudan.
7. Department of Public Health and Community Medicine, Faculty of Medicine, Beni-Suef University, Beni-Suef, Egypt.
8. Pediatric Dentistry and Dental Public Health Department, Faculty of Dentistry, and Faculty of Medicine, Cairo University, Cairo, Egypt.
9. Department of Public Health and Community Medicine, Faculty of Medicine, Cairo University, Cairo, Egypt.
10. Department of Oral Rehabilitation, Faculty of Dentistry, University of Khartoum, Khartoum, Sudan.
11. Amman, Jordan.
12. Department of Community Medicine, Public Health and Epidemiology, Faculty of Medicine, Cadi Ayyad University, Marrakesh, Morocco.
13. Department of Epidemiology and Public Health, Faculty of Medicine of Fez, Sidi Mohamed Ben Abellah University, Fez, Morocco.
14. Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA.